Efficient mineralization of phenol in high chloride solutions via Fenton reactions using γ-Cu2(OH)3Cl as a catalyst

gamma-Cu-2(OH)(3)Cl is used as a Fenton catalyst to mineralize phenol in high chloride solutions. The mineralization of phenol can be enhanced even at 15000 mg.L-1 NaCl under ambient pH. In addition, other aromatic contaminants including bisphenol A, benzoic acid, 2-chlorophenol, salicylic acid and aniline can also be effectively mineralized under the high chloride concentration. However, reference catalysts including CuSO4, CuO and Cu2O are significantly depressed by chloride. The chloride resistance ability of gamma-Cu-2(OH)(3)Cl is proposed. First, sigma-Cu-ligand complexes formed between Cu2+ and phenolic hydroxyl can react with H2O2 to promote the rapid reduction of Cu2+ to Cu+, which are not hindered by chloride. Second, the self-redox property of gamma-Cu-2(OH)(3)Cl which initiates the electron transfer from H2O2 to Cu2+ to generate Cu+ is improved by chloride. Third, the circumneutral pH could suppress HO center dot scavenging by chloride. The activation energies of phenol mineralization over gamma-Cu-2(OH)(3)Cl in chloride-free and high chloride solutions are 42.9 and 32.3 kJ.mol(-1), respectively. Chloride does not change the phenol mineralization pathway but accelerates its degradation into small carboxylic acids.